For weeks, people have been wondering why Scott hasn't been popping up on their smartphones to host the daily trivia show ... and we've learned it's because the "Quiz Daddy" left HQ in the dust after striking out in his quest to add a new nightly MLB show and keep his HQ gig.

Scott's last appearance on HQ Trivia was March 24 ... right before he announced he was accepting a second hosting gig with DAZN's new show called, "ChangeUp."

Sources at HQ Trivia tell us, Scott was trying to work out an arrangement to stay on as the weekend host for HQ, but CEO Rus Yusupov wouldn't budge.

For his part, Scott tells us there is anything but hard feelings. He tells TMZ, "Nothing in my decade-plus entertainment career has meant more to me personally and professionally than my involvement with HQ." He couldn't be more grateful for all the people who grew the co., and for the "HQties" who kept it thriving.

He states, "While the decision to leave HQ was a difficult one, I am delighted to begin this next chapter in my career with the amazing people at MLB and DAZN. If you miss me on HQ, you can now get three hours of me every weeknight watching ChangeUp on DAZN."